Various types of combustion processes have been used in internal combustion engines such as the spark ignition process and the diesel process. In the spark ignition process, the flame front travels through the mixture and in the diesel process combustion progresses as the fuel and air is mixed.
Another combustion process is the experimental use of a homogeneous fuel-air mixture in which the entire mixture is ignited spontaneously by a high mixture temperature. However, this process results in excessive noise and engine damage.
The present invention is directed to a process and an engine using a homogeneous mixture of fuel and air which is ignited spontaneously by high mixture temperatures produced by heating and by compression of the fuel charge which uses engine exhaust products to control the high heat release rates, and avoids the complication of power absorbing high pressure fuel injection systems and combustion air throttle systems. The present invention does not throttle the combustion air and uses a heater element in the combustion chamber to precondition the fuel-air mixture. The present process and engine has the advantage in that the efficiency is similar to that of a diesel engine and is higher than a spark ignition engine.